1. Field of the Invention
The present invention relates to an original scanning device (i.e., scanner) which has a scanning means being reciprocated.
2. Related Background Art
In a conventional image reading apparatus which has a scanning device being reciprocated, in order to accurately stop the reciprocated scanner at a home position for next reciprocation, a control is performed to stop the scanner at the home position by starting a brake operation when the scanner backwardly moved (or backed) reaches a predetermined position. Since this control merely requires anytime a constant brake control, the scanner can be accurately backed to the home position without any complicated structure. This control is based on a premise that a scanner speed when the scanner backed to the predetermined position is always maintained at a certain constant speed.
However, in recent copy machines, a maximum speed (especially in backward movement) of the scanner becomes higher than that of the conventional scanner because of improvement in productivity. Inevitably, the scanner speed at the predetermined position in the backward movement also becomes higher, so that a problem occurs when the above brake control is used. That is, when a scanning distance of the scanner is short because an original size is small, a copy magnification is large, or the like; if the scanner is backed from a scan termination position, the scanner speed sometimes does not yet reach the above certain constant speed at the time when the scanner just backed to the predetermined position. Therefore, if the brake operation is started in this state, the scanner undesirably stops at a position before the home position.